Fluorescent lamp lighting circuits



July s, 1958 Filed Aug. 9, 1954 W. A. CHARBONNEAUX FLUORESCENT LAMPLIGHTING CIRCUITS INPUT 2 Sheets-Sheet 1 FIG. 2..

EF (EFFECTIVE LAMP VOLTAGE LAMP STARTS INVENTOR WILSON A. CHARBONNEAUXAT TORNEY y 1958 w. A. CHARBONNEAUX 2,

FLUORESCENT LAMP LIGHTING CIRCUITS Filed Aug. 9, 1954 2 Sheets-Sheet 2 CS 4 k HM m FIG.4. 4

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Hid/2i 1 FIG 7 INVENTOR. WILSON A. CHARBONNEAUX e Aww W ATTORN EY UnitedStates Patent FLUORESCENT LAMP LIGHTING CIRCUITS Wilson A. Charbonneaux,Dayton, Ohio Application August 9, 1954, Serial No. 448,426

3 Claims. (Cl. 315-184) This invention relates to certain new and usefulimprovements in fluorescent lamp lighting circuits.

At the present time, fluorescent and similar gas-filled discharge-typelamps for interior illumination in homes, plants, factories, andwarehouses are conventionally used with a ballast which provides amomentary high starting voltage necessary to initiate ignition in suchlamps. The ballast, furthermore, operates to limit operating voltagesubsequent to ignition. Such ballasts conventionally comprise a combinedauto transformer and choke and consequently possess severaldisadvantages, such as a continuous high power loss, a lagging powerfactor which adds to the normal lagging power factor of other loads, andtemperature rise during operation which creates insulation problems andlimits practical use to conventional 110 v. and 240 v. lighting circuitsdespite the fact that great economies in installation and operatingcosts could be achieved with higher line voltages.

It is, therefore, the primary object of the present invention to providefluorescent lighting circuits by which fluorescent lamps and similardevices can be started promptly and efliciently across high voltagecircuits and operated with a minimum of current consumption and powerloss.

It is another object of the present invention to provide fluorescentlighting circuits which are substantially more economicalthan existingfluorescent lighting circuits, both as to initial installation costs, aswell as operating costs.

It is a further object of the present invention to provide fluorescentlighting circuits by which a multiplicity of fluorescent lamps can belighted and economically operated on higher voltage circuits, that is tosay, for instance, a 440 v. circuit and similar circuits of the typeusually available in industrial plants.

With the above and other objects in View, my invention resides in thenovel features of form, construction, atrangement, and combination ofparts presently described and pointed out in the claims.

In the accompanying drawings (two sheets) Figure l is a schematic wiringdiagram of a fluorescent lighting circuit embodying the presentinvention; 7

Figure 2 is a graph showing the voltage relationship in the circuit ofFigure l; and

Figures 3, 4, 5, 6, and 7 are modified forms of fluorescent lightingcircuits embodying the present invention.

Broadly speaking, the present invention resides in the discovery thatfluorescent lamps and similar devices having similar starting andrunning characteristics can be very efliciently started at ordinary roomtemperature and even at lower ambient temperatures by the utilization ofan A. C. series circuit consisting of a capacitor and current limitingimpedance in series with the lamp and a shunt circuit around the lamp,which latter circuit includes a rectifier. The rectifier is preferablyof the cold-cathode gaseous discharge type and will provide a peakinstantaneous voltage of approximately twice the instantaneous peakvalue of the A. C. line voltage, due to the fact that the capacitorremains charged only during successive half cycles of opposite polarity.Since the lamp acts as a very high resistance element before lighting,the capacitor will remain charged to its maximum potential until thelamp lights. This potential builds up in the capacitor until it issufficiently in excess of the ionization voltage of the lamp to causethe lamp to flash and become lighted. Several half-cycles may berequired depending upon the impedance of the reactor or other currentlimiting device, the impedance of the rectifier, and the time-constantof the circuit. Since the maintenance or operating potential of such alamp is much lower than its ionization potential, the lamp will bemaintained in lighted condition on ordinary line voltage. In thisconnection, it should be noted that all references herein to a line"imply an A C. line.

Referring now in more detail and by reference characters to thedrawings, which illustrate practical embodiments of the presentinvention, Figure 1 schematically represents a fluorescent lamp lightingcircuit comprising an inductive reactor L, a rectifier R, a capacitor C,a single pole single throw switch S, and a fluorescent lamp F, all beingconnected as shown.

As soon as voltage is applied across the line and the switch S closed,current will flow through the inductive reactor L, capacitor C, andthence through the rectifier R around the lamp F to complete thecircuit. The instantaneous voltage. rises to the firing potential of therectifier R, thus charging the capacitor C. If the lamp F does not lightat this value of potential, the charge remains on the capacitor C.Assuming the capacitor has charged to full peak-value, then on the nextcycle the lamp will have twice the peak-value of line voltage upon it atthe peak of the next half cycle. When the lamp lights, the voltage dropacross it will return to the operating value which is ordinarilyone-half to one-third of the starting voltage.

If the voltage applied across the lines, for example, is 440 v., cycle,the rectifier R should be designed to have an initial firing potentialsomewhere between the starting and operating voltages of the lamp, thatis to say, somewhere in the range of 425 v. to 475 v. and it will passcharging current when the instantaneous value of each positivehalf-cycle approaches such firing potential. Thus, the rectifier Roperates as a regulating valve to pass charging current to the capacitorC during each positive half-cycle (or negative half-cycle, dependingupon the arrangement of polarity within the circuit), but the rectifierR does not allow the capacitor C to discharge. Hence, the charge in thecapacitor C builds up until a D. C. potential is reached suflicient tocause the fluorescent lamp F to start on a succeeding negativehalf'cycle. If the lamp F, for example, when connected in a circuitacross a 400 v. line, has a starting potential requirement of 800 v. andan operating potential (after lighting) of only 200 v., the potential ofthe capacitor C (within a few cycles after closing the switches) adds tothe A. C. voltage of the line, resulting ina total of twice peak voltageevery cycle (2 400 1.41), thus furnishing more than suflicient voltageto light the lamp F. Immediately, however, with impedance of propervalue, the lamp voltage would drop to 200 v. and the rectifier R wouldbecome inoperative. Figure 2 shows diagrammatically the voltage andcurrent relationship with respect to time, as same occur in the circuitof Figure 1.

In the event the lamp F is inoperative, or is removed from its sockets,the rectifier R passes only suflicient current to maintain the charge onthe capacitor C. No appreciable power is consumed, therefore, when thelamp F does not light. Furthermore, since the rectifier R does notoperate at the lamp operating voltage, no power is consumed by therectifier R when the lamp F is glowing.

Although the circuit implies use in connection with fluorescentlighting, the invention is not limited to fluorescent lighting, butextends to other devices having similar starting and runningcharacteristics. Furthermore, the impedance L could be a resistanceelement, if desired.

Figures 3, 4, 5, 6, and 7, show modifications of the basic circuit abovedescribed, each including the lamp F, an impedance L, a capacitor C, anda switch S. The circuit of Figure 3, however, includes a rectifier Rwhich has a starter anode connected to the cathode thereof. The circuitof Figure 4 includes a rectifier R which has a starter anode connectedto the main anode thereof. The circuit of Figure 5 includes'a rectifierR which has a starter anode connected across the cathode and main anodeby a voltage divider Z for control of the magnitude of the startervoltage. The circuits of Figures 6 and 7 include rectifiers R and R",respectively, which have starter anodes connected across the impedance Lby voltage dividers Z and Z respectively, for controlling the amplitudeand phase of the starter voltage.

It should be understood that changes and modifications in the form,construction, arrangement, and combination of the several parts of thefluorescent lamp lighting circuits may be made and substituted for thoseherein shown and described without departing from the nature andprinciple of my invention.

Having thus described my invention, what I claim and desire to secure byLetters Patent is:

l. A circuit for fluorescent lamps and devices having similar loadcharacteristics, said circuit comprising a fluorescent lamp, a reactorand capacitor in series with opposite terminals of the lamp, and arectifier of the coldcathode gaseous discharge type shunted across theterminals of the lamp, said rectifier having a starter anode connectedto its cathode.

2. A circuit for fluorescent lamps and devices having similar loadcharacteristics, said circuit comprising a fluorescent lamp, a reactorand capacitor in series with opposite terminals of the lamp, and arectifier shunted across the terminals of the lamp, said rectifierhaving a starter anode connected to its cathode.

3. A circuit for fluorescent lamps and devices having similar loadcharacteristics, said circuit comprising a fluorescent lamp, a lineconnected to a source of current having a potential greater than thenormal operating potential of the lamp but less than the ionizationpotential of said lamp, said lamp being connected across said line, aninductance and a'capacitor interposed on opposite sides of the line inseries with the lamp, a shunt circuit around the lamp, and a rectifierof the cold-cathode gaseous discharge type interposed in said shuntcircuit, said rectifier having a starter anode connected to its cathode.

References Cited in the file of this patent UNITED STATES PATENTS2,130,077 Dorgelo Sept. 13, 1938 2,575,001 Bird Nov. 13, 1951 2,614,243Clark Oct. 14, 1952

